Thermal appliances, such as ovens, generally have a cavity (also referred to a “heat capacity room”) and a door configured to cover one end of the cavity. In order to prevent heat inside the cavity from escaping through the space between the cavity and the door when the door is closed, a gasket may be used to fill the space. The gasket may include an inner support and an outer tubular member made of, for example, glass fiber. It is desirable to provide a properly designed structure and configuration of the inner support to support the outer tubular member when the outer tubular member is pressed by other components of the oven such as the door and the cavity.